Method of solder tipping keys



- June 3, 1941.

G. A. VBARDET ETAL METHOD OF SOLDER TIPPINiv KEYS sheets-Sheet 1 `FiledNOV. 1. 1937 l ENTO'R I foeaf `.4a/:RW -r l 6501265 V. GHZDET MHATTORNEY June 3, 1941. 'G. A. BARDET ETAL METHOD OF SOLDER TIPPING KEYSFiled Nov. 1, 1937 2 Sheets-Sheet 2 ATTORNEY Patented June 3, 1941vliillllllOD OF SOLDER TIPPING KEYS George A. Bardet and George V.Bardet, Berkeley,

Calif., assignors to M. J. B. Company. San Francisco, Calif., acorporation of Delaware Application November 1, 1937, Serial No. 172,220

1Claim.

This invention relates to a method ci and an improved means for soldertipping keys such as those which are used for the removal of the tearingstrips from metal cans and containers; the tipping of the keys with a.solder bead or lug being for the purpose of providing a means wherebythe keys subsequently may be aillxed to the cans, thus to insure thatwhen it is desired to open a can, a key will be available for thatpurpose merely by breaking it loose from the can wall,

It is the principal object of this invention to improve upon that methodof key tipping or dipping that is disclosed in the patent of G. A.Bardet et al., issued January 20, 1931, No. 1,789,722, and also toimprove upon the machine of that patent in a certain feature whereby thesolder lug is prevented from being drawn out beyond the nd of thekey'shank.

Explanatory to the present invention, it will here be stated that it isnow a practise quite generally followed to attach .the tearing stripkeys to cans by applying a small lug of solder to the ends of the keys,then to place the keys upon the end wall of the cans and to apply anelectrode of an electric circuit against the solder tipped part oi thekeys whereby to cause the solder to be melted; it being understand that,upon removal oi' the electrode, the solder will set and thereby solderthe key to the can wall.

Keys oi this kind are, as a rule, formed from steel wire. Sometimes thekeys are plated with a copper wash prior to solder tipping. Suchplatlng, while it may be desirable in some instances, has no bearing onthe present invention. The difficulty experienced in solder tipped keysbreaking loose from the can prior to use is generally due to the factthat there is not a sufiicient bond formed between the key shank and thesolder, and this is because the key shank. at the time oi' tipping itwith solder, is not brought up to a temperature sufficient to cause aconnection by penetration of solder into the keyv metal, but since thekey is dipped while relatively cold, the solder merely forms a coatingwithout any Permarient bond. Therefore, this invention is directed to amethod of eiiecting a'holding bond between the key shank Vand the solderlug, and to insure a solder lug oi' a necessary size, that when the keyis once attached to the can, it can not be broken loose except by anapplication of the intended amount of pressure or pull on it.

It is a further object of the invention tc improve upon certain detailsoi construction oi' the key dipping machine oi the prior patentl so thatwhen the tip of the key is lifted from the solder bath, the lug adheringthereto will not be drawn out to an elongated point but will be wipedofi hush with or adjacent the end of the key.

More specifically, the present method resides in eecting a .betteradherence of the solder lug by reason of a ilrst and second dippingoperation in which thevrst is oi.' relatively long duration and in alhotter mixture to insure heating of the key to a degree at which thesolder will fuse with the key metal to forma permanent bond, asdifferentiated from a coating, and wherein the second dip is relativelyshort and in a mixture of lower temperature to cause the adherence oi" agreater amount.

Other objects of the invention reside in the details of constructionoi.' the machine, in the combination of parts, and in their mode ofoperation, as will hereinafter be fully described.

In accomplishing these and otherobjects of the invention, we haveprovided the improved details of construction, the preferred forms ofwhich are illustrated in the accompanying drawings, wherein- Flg. 1 is aside view of a key dipping machine embodied by the present invention.

Fig. 2 is a plan view of the same.

Fig. 3 is an enlarged sectional detail longitudinally of the keyguideway and conveyers whereby the keys are advanced through the variousdipping operations.

Fig. 4 is a sectional detail of the key magazine and key feedingmechanism of the machine.

' Fig. 5 is a plan view of the key feed slide.

Fig. 6 is an enlarged view of the key lifting cam.

Fig. 'l is an enlarged cross section of a processed key.

Referring more in detail to the drawings- 'I'he present machinecomprises a main frame structure designated in its entirety by referencenumeral I, including spaced longitudinal bars 2 and 2', disposed in thesame horizontal plane and joined ltogether at spaced intervals by crossframes 3. Upon one end of the main frame l is a key feed table l,supported by frames 4a and erected upon the feed table at its forwardedge is a vertical magazine 5 provided with a passage 5a within whichthe keys 6 to be dipped are stacked, in such manner that the stack willfeed downwardly in accordance with the successive discharge of keystherefrom at the lower end oi the magazine.

Supported by one of the cross frame members 3 of the main framestructure I, just forwardly of the table 4, is open top container Iwhich contains a soldering flux, and in alinement with this fluxcontainer is a rather elongated container 9 wherein tinning solder iskept ln a molten state at approximately 480 F. At some distance spacedfrom the solder pot 9, and also in alinement therewith, is a secondsolder potI l of relatively short length in which a second dip oftinning solder is contained; this being kept at a temperature ofapproximately 460 F.

Extending from the feed table 4 directly over the flux and soldercontainers is a key track and guideway that is formed by two plates I!and I2'. These are disposed in the same horizontal plane and areslightly spaced. At their ends, they are fixed to parts-of the mainframe and are held rigid. These plates are arranged with their adjacentedges in spaced relation whereby to provide an intermediate slot I4 fromend to end of the guideway for the travel of keys therein. At thereceiving end, the slot terminates in alinement and registration with adischarge slot 5a provided in the lower end of the key supply- .ingmagazine 5, and it is of such width that the shank portions only of thekeys may drop therethrough, and the keys will be held suspended by theloop ends as they are moved along the guideway successively over thecontainers 1, 9 and Il. Provision is also made to so suspend the keysthat, in their travel, their lower end portions will be dipped first inthe soldering flux of container 1, then in the solder of hightemperature in container 9, and finally, after passing through a coolinginterval, to be dipped in the solder of low temperature contained in potII.

The means herein provided for advancing the keys along the guidewaycomprises paired chain conveyor belts Ii which operate together, and inparallel relation at opposite sides of the slot both above and below theplates I2 and I2. Cross bars I1 extend between the two belts above andthe two belts below the guideways for engaging the keys in such manneras to push them along the slot. As here illustrated, the conveyer beltsare carried by sprocket wheels Il on cross shafts Il extended betweentransversely alined standards Il. The movement of the four belts issynchronized through intermeshing gears and 2l' that are fixed to theends of shafts l! for upper and lower belts and they are driven by asprocket wheel 23 fixed on a shaft I! and also about a sprocket 24 fixedon a driven shaft 26. In the present instance an electric motor 28 isprovided as the driving means, and this has its shaft 2l connectedthrough gear reduction mechanism il and belt Il with he shaft 2l.

cross shaft Il revolubly mounted in bearings Il in the lower ends ofbrackets l1 that are fixed to the under side of the frame structure. Theshaft 5I is driven by intermeshing gears 5l and 5l on the shafts 55 and$8; the shaft l! being driven by a belt chain il from shaft 26 to shaft59, and rotation of shaft Si causes the wheel i4 and link 5I to impartmotion to the shaft 41 and lever 45. which in turn, causes reciprocalaction of the feed slide to deliver the keys, one at a time, into theguideway.

The keys are so positioned in the magazine that they will be pushed outwith the looped end Located centrally on the table top 4 in thelongitudlnal direction' of the machine are parallel guides 3I-38 andreciprocally contained between these is a feed block l! to which oneencl of a key feed slide 40 is fixed. The forward end ofthe feed slideis adapted, on each forward movement of the block, to engage and pushthe lower key of the stack from the magazine and into a position atwhich it will be taken up and advanced through the machine by the crossbars of the synchronized conveyer belts. 'I'he slide is reciprocallyactuated by a lever 45 to which it is pivotally connected through themediacy of a link 4I. The lever 45 is fixed horizontally to the upperend of a rocker shaft 41 carried on a vertical sleeve 48 fixed to themain frame structure. At its lower end, the shaft 41 has a lever arm 5lfixed thereto and this is connected at its end to a link Il which, inturn, is connected pivotally and eccentrically to a wheel 54 on the endof a forward, whereupon the shank portion will fall of its own weightdownwardly through the slot p i4 and will be held in a suspendedposition by the key loop. When the feed slide is retracted. the shankportion of the lower key in the supply magazine drops into the slot I0;then, as the slide is advanced, its forward end portions at oppositesides of the slot, engage with the loop of In order that the dependinglower end portions l of the keys may be dipped in the flux and solder,yet not come into engagement with the end walls of the flux and solderpots, provision is made for lifting the keys at the proper intervals.The means for effecting this lifting comprises cam lugs 60 located onthe plates I2-I2' in the same transverse planes of these walls of theflux and solder pots, and across which lugs the supporting loops of thekeys are caused to ride as the keys are advanced. These cam lugs are.lust of sufficient height that, in passing thereover, the lower ends ofthe keys will be carried clear of the top edge of the end walls of thepots. Immediately after a key has been carried across the end wall ofthe flux or solder pot, it is lowered so that its tip end will be dippedto proper extent. It will be understood that in tipping a key end, theend is first carried through the flux pot 1 to immerse the part of thekey to be tipped; then it is likewise carried through the first solderdip for fusing the plating with the key metal, and also fusing a basecoat of solder to the key.

A feature of the present invention resides in the fact that the firstsolder pot is of considerable length and the solder therein ismaintained at a relatively high temperature. This provides that the keywill remain in the solder for a relatively long interval of time duringwhich the key becomes thoroughly heated and the solder penetrates themetal and forms a permanent bond therewith. Then the keys are cooled bybeing carried through the interval between the nrst and second solderpots i and I0. A water cooling vat may be interposed here if necessary.The keys are finally carried through the second solder dip which is ofrelatively short duration. and it is only necessary that they bemomentarily dipped because this solder quickly and readily adheres tothe base coat. Furthermore, by having the solder of the second dip at alower degree of temperature, a lug of substantial and adequate size willadhere to the'key.

As a feature of the invention, provision is herein made that this lug ofsolder will not be drawn out to a long tipwhen the key is lifted. Toaccomplish this, I have provided cams 1I on the plates I2l2' at oppositesides oi' the slot for rst just slightly elevating the key while it isstill passing through the second solder pot so 'certain cooling intervalso that the keys, as they are delivered from the machine, will notadhere to each other.

The features of this invention reside, first, in applying a dip oisolder, as at A in Fig. 7, that is of relatively high temperature andretaining the key therein through a. considerable period of time so thatthe solder coat will penetrate and be thoroughly united with the 'keymetal, and nally dipping the key in a solder of lower temperature iorcausing the formation of a ball or knob of solder at the key end as at Bin Fig. 7.

The feature of improvement in the machine resides in the provision ofthekey lifting cam associated with the second dip, which lifts the key justsumcient that the lower tip will wipe the top surface of the solder,thus to wipe of! that part of the solder bell that otherwise would bedrawn out to a point extending from the key end.

After the keys are thus solder tipped, it is desirable that they betinned in order to prevent corrosion. This' would be done in the usualway so that the entire key and solder lug is coated. Having thusdescribedv our invention, what we claim as new therein and desire tosecure by Letters Patent is- 1 The method of solder tipping keys whichoomprises first applying a solderingjiluxv tothe key end, then insertingthe end of the key shank vertically into molten solder of relativelyhigh temperature, and maintaining it there for a period sunicient toheat the key shank to approximately the temperature or the solder, andto cause it to' be coated with the solder. then cooling, and iinallyinserting the coated part of the key shank momentarily in molten solderof a lower temperature just slightly above its melting point,withdrawing the shank Vand wiping oil the lower end of the bead bymoving the key while held 'vertically across the top of the moltensolder.

GEORGE A. BARDET. GEORGE V.v BARDET.

